Dissertations / Theses on the topic 'Spiral Wound Module'

To see the other types of publications on this topic, follow the link: Spiral Wound Module.

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 24 dissertations / theses for your research on the topic 'Spiral Wound Module.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

El-Shamy, Awad. "Effect of permeate suction on the performance of spiral wound nanofiltration module." [Tampa, Fla.] : University of South Florida, 2009. http://digital.lib.usf.edu/?e14.2868.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

El-Shamy, Awad Abdel Monem. "Effect of Permeate Suction on the Performance of Spiral Wound Nanofiltration Module." Scholar Commons, 2009. https://scholarcommons.usf.edu/etd/1949.

Full text
Abstract:
Fouling in a nanofitration membrane module is usually a result of concentration polarization. The effect of permeate suction on the slightly negatively charged spiral wound nanofiltration membrane is investigated. According to the film theory, the mass transfer coefficient is inversely proportional to concentration polarization. The effect of permeate suction destabilizes the boundary layer. This will decrease the concentration polarization layer, and consequently will increase mass transfer through the membrane's surface. To validate the hypothesis, experiments were carried out on a NF membrane that can be described by the solution-diffusion model. This model has coefficients that can be measured experimentally. Using the membrane wall concentration in this model instead of the bulk feed concentration can help estimating the mass transfer coefficient more appropriately. Two experimental studies were carried out, one with a standard high pressure pump, and another one with the added effect of suction pressure applied to the permeate collector tube. Three different concentrations of binary dilute solutions of NaCl, MgSO4, and MgCl2, at three different pressures (low, medium, and high) were tested. For all tested solutions, permeate suction increased the diffusive Peclet number as a function of the feed concentration (x) according to the equation Pe = a1x²+b1x+c1, with R²>0.99, where x is the feed concentration in Mol/l, and a1, b1, and c1 are coefficients dependent on feed pressure for every salt solution. With the increase of the Peclet number, it was observed that the concentration polarization decreased, and both the product flow and the product quality were improved. Suction had the greatest impact at the range of 100 to 110 psi feed pressure, where the concentration polarization reduced approximately 14 to 20 %. ANOVA for the concentration polarization showed that suction was significant in reducing the calculated concentration polarization layer for all tested solutions. It was concluded that permeate suction reduced concentration polarization, increased product flow rate, and improved product quality. Thus, adding permeate suction has beneficial consequences because it reduces membrane fouling and extends its useful service life.
APA, Harvard, Vancouver, ISO, and other styles
3

Hartinger, Martin [Verfasser]. "Milk protein fractionation by spiral-wound membranes - Optimization of process and module design / Martin Hartinger." München : Verlag Dr. Hut, 2021. http://d-nb.info/1235279413/34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Fimbres, Weihs Gustavo Adolfo UNESCO Centre for Membrane Science &amp Technology Faculty of Engineering UNSW. "Numerical simulation studies of mass transfer under steady and unsteady fluid flow in two- and three-dimensional spacer-filled channels." Publisher:University of New South Wales. UNESCO Centre for Membrane Science & Technology, 2008. http://handle.unsw.edu.au/1959.4/41453.

Full text
Abstract:
Hollow fibre and spiral wound membrane (SWM) modules are the most common commercially available membrane modules. The latter dominate especially for RO, NF and UF and are the focus of this study. The main difficulty these types of modules face is concentration polarisation. In SWM modules, the spacer meshes that keep the membrane leaves apart also help reduce the effects of concentration polarisation. The spacer filaments act as flow obstructions, and thus encourage flow destabilisation and increase mass transfer enhancement. One of the detrimental aspects of the use of spacers is an increase of pressure losses in SWM modules. This study analyses the mechanisms that give rise to mass transfer enhancement in narrow spacer-filled channels, and investigates the relationship between flow destabilisation, energy losses and mass transfer. It shows that the regions of high mass transfer on the membrane surface correlate mainly with those regions where the fluid flow is towards the membrane. Based on the insights gained from this analysis, a series of multi-layer spacer designs are proposed and evaluated. In this thesis, a Computational Fluid Dynamics (CFD) model was used to simulate steady and unsteady flows with mass transfer in two- and three-dimensional narrow channels containing spacers. A solute with a Schmidt number of 600 dissolving from the wall and channel Reynolds numbers up to 1683 were considered. A fully-developed concentration profile boundary condition was utilised in order to reduce the computational costs of the simulations. Time averaging and Fourier analysis were performed to gain insight into the dynamics of the different flow regimes encountered, ranging from steady flow to vortex shedding behind the spacer filaments. The relationships between 3D flow effects, vortical flow, pressure drop and mass transfer enhancement were explored. Greater mass transfer enhancement was found for the 3D geometries modelled, when compared with 2D geometries, due to wall shear perpendicular to the bulk flow and streamwise vortices. Form drag was identified as the main component of energy loss for the flow conditions analysed. Implications for the design of improved spacer meshes, such as extra layers of spacer filaments to direct the bulk flow towards the membrane walls, and filament profiles to reduce form drag are discussed.
APA, Harvard, Vancouver, ISO, and other styles
5

d’, Souza David. "Experimental Characterisation and Modelling of a Membrane Distillation Module Coupled to aFlat Plate Solar Collector Field." Thesis, Högskolan Dalarna, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:du-28186.

Full text
Abstract:
An experimental characterisation of a pre-commercial spiral wound permeate gap membrane distillation module was carried out to test its performance at different operating conditions for the purpose of seawater desalination. The experimental setup consisted of a flat plate solar collector field indirectly coupled to the permeate gap membrane distillation module via an inertia tank. The operating parameters varied were the condenser inlet temperature (from 20 °C to 30 °C), evaporator inlet temperature (from 60 °C to 80 °C) and seawater feed flow rate (from 200 l/h to 400 l/h). Within this operational boundary, it was found that the maximum permeate/distillate flux was 4.135 l/(h∙m2) which equates to a distillate production/flow rate of close to 21.3 l/h. The maximum potential distillate production rate is expected to be significantly higher than this value though as the maximum manufacturer specified feed flow rate is 700 l/h and the maximum evaporator inlet temperature is rated at 90 °C. Both these parameters are positively related to the distillate production rate. The minimum specific thermal energy consumption was found to be 180 kWh/m3. A mathematical model of the overall system was developed, and experimentally validated, to mathematically describe the coupling of the membrane distillation module with a solar collector field. The effectiveness of internal heat recovery of the membrane distillation module was found to be an accurate and simple tool to evaluate the thermal energy demand of the distillation process at a given set of operation parameters. The mathematical model was used to further investigate the experimental findings and provide insights into the operational dynamics of the membrane distillation module. It was also used to determine some external conditions required for steady state operation, at a given distillation operating point, such as the minimum solar irradiation required for operation and the auxiliary cooling required in the solar collector loop for maintaining steady state conditions. Finally, general guidelines are provided toward better operational practices to improve the coupling of a solar thermal collector unit/field with a membrane distillation system using a storage tank or inertia tank.
APA, Harvard, Vancouver, ISO, and other styles
6

Chen, Kai. "Facilitated Transport Membranes for Fuel Utilization Enhancement for Solid Oxide Fuel Cells and Carbon Capture from Flue Gas." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595196886200366.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Al-Obaidi, Mudhar A. A. R. "Modelling, Simulation, and Optimisation of Reverse Osmosis Process with Application in Wastewater Treatment and Food Processing." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17345.

Full text
Abstract:
Reverse Osmosis (RO) is a membrane-based separation process applied in several industrial and food processing applications. In this research, performance of RO process is investigated in respect of two applications (a) wastewater treatment (b) concentration fruit juices using model-based techniques. For this purpose, a number of models (both 1 and 2-dimensional steady state and dynamic) for spiral wound RO process are developed based on Solution-Diffusion model and Irreversible Thermodynamic model. The models are validated against actual experimental data reported in the literature before being used in further simulation and optimisation studies for both wastewater treatment and fruit juice concentration. Wastewater effluents of many industrial applications contain a variety of micro-pollutants and highly-toxic compounds, which are released into a variety of water resources. Such pollutants not only disrupt the biological ecosystem, but they also pose a real threat to the water supply for human consumption and to the aquatic ecosystems. The earlier chapters of the thesis evaluate the performance of RO process in terms of removal efficiency of toxic compounds such as chlorophenol, N-nitrosamine, etc. from wastewater. The effect of several operating parameters such as feed pressure, concentration, flow rate and temperature, on the performance of RO process are evaluated. Also, suitability of a number of different RO configurations for efficient removal of toxic compounds are evaluated. For example, (a) two-stage/two-pass RO design synthesis of RO network for the removal of chlorophenol (b) multistage multi-pass RO process with and without energy recovery option for the removal of N-nitrosamine are investigated. The dynamic response of the RO process for step changes in the operating parameters is investigated for the removal of phenolic compounds. Finally, in the context of wastewater treatment, a case study with multi compounds contaminants is suggested where a multi-objective optimisation problem has achieved the optimum rejection of all the compounds and recovery rate. In respect of food processing, RO has been considered as a prominent process in fruit juice concentration due to its ability to effectively retain the flavour, sensory, aroma and nutritional characteristics and concentrate the juice. This research elucidates one example of apple juice concentration process and focuses on highlighting successful modelling and optimisation methodology. This in turn provides an efficient method of RO process for concentrating apple juice by improving the reliability and efficiency of the underlying separation and concentration process.
Ministry of High Education and Scientific Research of Iraq
APA, Harvard, Vancouver, ISO, and other styles
8

Wen, Tong. "Spirally wound electrodialysis (SpED) module." Thesis, Cranfield University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358252.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Iranshahi, Ashkan. "Static Mixing Spacers for Spiral Wound Modules." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1352121892.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Ben, Boudinar Mourad. "Performance prediction and optimisation of spiral wound modules." Thesis, University of Glasgow, 1991. http://theses.gla.ac.uk/3235/.

Full text
Abstract:
The work deals with the modelling and optimisation of reverse osmosis (RO) spiral wound elements. It is aimed at improving areas of uncertainty and possible limitations which remain with current published predictive schemes. These were compromised mainly by the lack of adequate experimental data representative of actual operating conditions. Two different mathematical models, termed the `Slit' and the `Spiral' model, were developed. These models differ on the geometrical idealisation of a spiral wound element as indicated by their names. The Solution Diffusion model is used to describe water and salt transport across the membrane. The differential equations governing the process were solved numerically using a finite difference method. The resulting computer programs enable concentrations, pressures and flow rates in the brine and permeate channels to be obtained at any point in the module. The investigation covered a wide range of feed conditions by using experimental data provided from two different types of commercial spiral wound modules. These were the ROGA-4160HR [29] and the Filmtec FT30SW2540 [28] modules. The former type dealt with data typical of brackish water desalination whereas the second type provided data typically encountered in sea-water desalination. The required intrinsic membrane characteristics were determined experimentally using small samples of membrane in a test cell in a closed loop system. For both models, the predictions agree very well with the experimental data over the entire range of operating conditions:- with the exception of some few cases, typical deviations were of the order of 6% for the module productivity and of about 10% for the permeate quality. In addition, parametric studies were performed to establish the programs consistency and the results were in accordance with the theory.
APA, Harvard, Vancouver, ISO, and other styles
11

Shi, Binchu. "Impacts of spiral-wound membrane modules in organic solvent nanofiltration applications." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/44570.

Full text
Abstract:
In recent years organic solvent nanofiltration has showed great potential in a number of industrial fields. A growing number of studies have been reported on development of new membrane materials, optimisation of membrane manufacturing conditions, enhancement of membrane performance and fundamental understanding of molecular transport through membranes. However, studies on spiral-wound membrane modules which are almost exclusively applied in industry are few. In this research project, experimental data on spiral-wound membrane modules of different sizes (from 1.8"x12" to 4.0"x40") in solutions covering a wide range of solute concentrations were collected under steady state operation. Then a procedure to obtain correlations describing fluid dynamics and mass transfer characteristics in the modules was developed using a limited number of experimental data for flat sheets and a 1.8"x12" module only. Furthermore, a multi-scale model for simulating the performance of processes using the modules was developed, considering the molecular transport through the membranes (membrane scale), the fluid dynamics and mass transfer characteristics in the modules (module scale) and the thermodynamic and physical properties of the solutions as a function of operating conditions (process scale). This model was used to simulate the performance of a batch concentration process using different modules under various operating conditions, and good agreement between simulation and experiments was found. In addition, the impact of ultra-high membrane permeance on process efficiency is examined in organic solvent nanofiltration and reverse osmosis as case studies via simulation, considering both concentration polarisation and pressure drops in modules. The key conclusion is that ultra-high permeance membranes will not be able to make a significant impact on process efficiency with current module designs; and the recommendation is that fresh research into module and process design is required.
APA, Harvard, Vancouver, ISO, and other styles
12

Ramasubramanian, Kartik. "CO2 (H2S)-SELECTIVE MEMBRANES FOR FUEL CELL HYDROGEN PURIFICATION AND FLUE GAS CARBON CAPTURE:AN EXPERIMENTAL AND PROCESS MODELING STUDY." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1374193903.

Full text
APA, Harvard, Vancouver, ISO, and other styles
13

Wagner, Ole. "Modelling and simulation of transport phenomena in open channel spiral wound modules for seawater desalination /." Düsseldorf : VDI-Verl, 2007. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015715135&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

Full text
APA, Harvard, Vancouver, ISO, and other styles
14

Njoki, Emmah. "Health promotion needs of youth with physical disabilities with specific reference to spinal cord injury in the Western Cape -- South Africa." Thesis, University of the Western Cape, 2004. http://etd.uwc.ac.za/index.php?module=etd&amp.

Full text
Abstract:
This study aimed to determine health promotion needs of physically disabled youth with spinal cord injury. The study specifically explored health-related behaviours with reference to participation in physical activity and substance usage, factors that influenced these behaviours and major issues that needed to be targeted in health promotion.
APA, Harvard, Vancouver, ISO, and other styles
15

Chen, Ching-Liang, and 陳靖良. "Characterization of membrane fouling in spiral wound module using high frequency ultrasound image analyses." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/77441935156673258012.

Full text
Abstract:
碩士
中原大學
化學工程研究所
100
The fouling phenomenon in spiral wound membrane modules was investigated using an ultrasonic time domain reflectometry (UTDR) and computational fluid dynamic (CFD). However, the UTDR with the lower frequency transducer has difficulty in analyzing the signals between inner and outer membrane surfaces of the same feed channel in spiral wound membrane modules. Purposes of this research were emphasized on the effects of the different membrane materials, placement types, operation time and feed velocity on the fouling phenomenon in spiral wound membrane modules. The results showed that the UTDR with the 50 MHz transducer had higher resolution so as to observe slight variation on the membrane surface. The fouling behavior was varied by the gravity and shear stress as the spiral wound membrane module set up horizontally. It was obviously understood differences between inner and outer membrane surface of the same feed channel owing to shear stress variations as the module set up vertically. As the membrane permeability of spiral wound membrane modules increased, the fouling area would be closed to the collection pipe. This tendency was agreed well with the CFD results. Therefore, the UTDR with high-frequency transducer could be used to analyze the slight variations of fouling phenomenon in spiral wound membrane modules.
APA, Harvard, Vancouver, ISO, and other styles
16

Al-Obaidi, M. A., Chakib Kara-Zaitri, and Iqbal M. Mujtaba. "Simulation and optimisation of spiral-wound reverse osmosis process for the removal of N-nitrosamine from wastewater." 2018. http://hdl.handle.net/10454/15360.

Full text
Abstract:
Yes
N-nitrosamine in wastewater treatment processes can contribute to several public health impacts including human carcinogens even at very low concentration. In this work, spiral-wound reverse osmosis (SWRO) process is used to remove N-nitrosamine compounds from wastewater. Effects of operating parameters of the SWRO process on the removal of N-nitrosamine, total water recovery, and specific energy consumption for a SWRO configurations are evaluated via simulation and optimisation. For this purpose, the one-dimensional distributed model developed earlier by the authors is modified by including different mass transfer coefficient correlation, temperature dependent water and solute permeability correlations and energy equations. The model is first validated by estimating a new set of model parameters using eight set of experimental data from the literature and is then used to simulate the process with and without energy recovery device to facilitate deeper insight of the effect of operating conditions on the process performance. The model is then embedded within an optimisation framework and optimisation problems to maximise N-nitrosamine rejections and to minimise specific energy consumption are formulated and solved while the operating conditions are optimized simultaneously.
APA, Harvard, Vancouver, ISO, and other styles
17

Al-Obaidi, M. A., Chakib Kara-Zaitri, and Iqbal M. Mujtaba. "Significant energy savings by optimising membrane design in multi-stage reverse osmosis wastewater treatment process." 2017. http://hdl.handle.net/10454/14582.

Full text
Abstract:
Yes
The total energy consumption of many Reverse Osmosis (RO) plants has continuously improved as a result of manufacturing highly impermeable membranes in addition to implementing energy recovery devices. The total energy consumption of the RO process contributes significantly to the total cost of water treatment. Therefore any way of keeping the energy consumption to a minimum is highly desirable but continues to be a real challenge in practice. Potential areas to explore for achieving this include the possibility of optimising the module design parameters and/or the associated operating parameters. This research focuses on this precise aim by evaluating the impact of the design characteristics of membrane length, width, and feed channel height on the total energy consumption for two selected pilot-plant RO process configurations for the removal of chlorophenol from wastewater. The proposed two configurations, with and without an energy recovery device (ERD), consist of four cylindrical pressure vessels connected in series and stuffed with spiral wound membranes. A detailed steady-state model developed earlier by the authors is used here to study such impact via repetitive simulation. The results achieved confirm that the overall energy consumption can be reduced by actually increasing the membrane width with a simultaneous reduction of membrane length at constant membrane area and module volume. Energy savings of more than 60% and 54% have been achieved for the two configurations with and without ERD respectively using process optimization. The energy savings are significantly higher compared to other available similar studies from the literature.
APA, Harvard, Vancouver, ISO, and other styles
18

Al-Obaidi, M. A., Chakib Kara-Zaitri, and Iqbal M. Mujtaba. "Simulation and sensitivity analysis of spiral wound reverse osmosis process for the removal of dimethylphenol from wastewater using 2-D dynamic model." 2018. http://hdl.handle.net/10454/16181.

Full text
Abstract:
Yes
Reverse Osmosis (RO) processes are readily used for removing pollutants, such as dimethylphenol from wastewater. A number of operating parameters must be controlled within the process constraints to achieve an efficient removal of such pollutants. Understanding the process dynamics is absolutely essential and is a pre-step for designing any effective controllers for any process. In this work, a detailed distributed two-dimensional dynamic (x and y dimensions and time) model for a spiral-wound RO process is developed extending the 2-D steady state model of the authors published earlier. The model is used to capture the dynamics of the RO process for the removal of dimethylphenol from wastewater. The performance of the 2-D model is compared with that obtained using 1-D dynamic model before the model is being used to investigate the performance of the RO process for a range of operating conditions.
APA, Harvard, Vancouver, ISO, and other styles
19

Al-Obaidi, M. A., A. A. Alsarayreh, A. M. Al-Hroub, S. Alsadaie, and Iqbal M. Mujtaba. "Performance analysis of a medium-sized industrial reverse osmosis brackish water desalination plant." 2018. http://hdl.handle.net/10454/16400.

Full text
Abstract:
Yes
The implementation of Reverse Osmosis (RO) technology is noticeably increased to produce freshwater from brackish and seawater resources. In this work, performance analysis of a multistage multi pass medium-sized spiral wound brackish water RO (BWRO) desalination plant (1200 m³/day) of Arab Potash Company (APC) located in Jordan is evaluated using modelling and simulation. For this purpose, a mathematical model for the spiral wound RO process based on the principles of solution diffusion model is developed. The model is then used to simulate the operating conditions of low-salinity brackish water RO (BWRO) desalination plant. The results obtained are then compared against the real industrial data of BWRO desalination plant of APC which shows a high-level of consistency. Finally, the model is used to analysis the impact of the operating parameters such as salinity, pressure, temperature, and flow rate on the plant performance. The sensitivity analysis confirms that both feed flow rate and operating pressure as the critical parameters that positively affect the product salinity.
APA, Harvard, Vancouver, ISO, and other styles
20

Siebdrath, Nadine. "Biofouling of membrane systems: characterization and impact of pre-treatment." Doctoral thesis, 2016. https://tud.qucosa.de/id/qucosa%3A30396.

Full text
Abstract:
Unrestricted use of reclaimed secondary effluents for irrigation is a major goal in countries suffering from water shortage. Reverse osmosis desalination is used to provide high quality waters with reduced salinity. In order to allow water production with high economic efficiency, fouling in the membrane installation needs to be minimized. Biofouling, caused by microorganisms synthesizing high-molecular biofilms, is of major concern. Biofouling reduces the water production rate and thus increases the costs of the process. Deeper knowledge on its formation and its impact on membrane performance is needed. This is relevant especially for large-scale treatment plants, where process conditions change over length and time and influencing factors on fouling formation occur in combination. Thus, in the present thesis a membrane test cell was developed which enables the investigation of biofouling under validated, representative conditions of full-scale modules. Biofouling was studied in order to determine its impact on membrane performance. Also, appropriate, cost-effective pre-treatment prior to the reverse osmosis process minimizes fouling. Therefore, biofiltration and its suitability as stand-alone pre-treatment was studied when reusing secondary effluents with reverse osmosis. The developed membrane test cell of 1 m length can be assembled with further test cells to simulate a spiral wound module alone, as well as several modules in series in a pressure pipe. The test set-up enables the systematic study of fouling formation integrative over the full length of industrial spiral wound modules. All performance parameters (feed channel pressure drop, permeability/flux, and salt passage) can be monitored over the full length and locally connected to accumulated foulants (non-destructive fouling diagnosis). Validation studies demonstrated that the hydraulic conditions (relationship between pressure drop and flow velocity, as well as the flow profile) are exactly as in real spiral wound modules. Each test cell is a representative, validated system of full-scale dimensions and hydraulics. It was further found that for fouling formation investigations, feed spacers with the same thickness as the feed channel height need to be used. In this way, accurate experimental measurements, especially of feed channel pressure drop, are ensured. With the developed test cells, the impact of biofouling on membrane performance was determined under conditions similar to practice. Biofouling resulted in a decline of all membrane performance parameters. Feed channel pressure drop was affected earliest and most severely, indicating its suitability as a sensitive biofouling monitoring parameter. Salt rejection was moderately impacted by biofouling and influenced by several process parameters, reducing its applicability as monitoring parameter. It was further found, that most biofilm accumulated in the lead parts of the membrane test cells with a declining gradient towards the tail sections. The gradient of biofouling over the length of the membrane installation was directly referred to the declining availability of easily assimilable substrate. It emphasizes the importance to reduce the concentration of biodegradable nutrients in the feed to the membrane installation as suitable strategy to restrict biofouling. The high amount of biofilm deposits in the lead parts caused feed channel pressure drop increase over the lead test cell and affected negatively the performance of the downstream test cells: The tail test cells showed a moderate decline for the permeability (flux) and salt rejection. Biofiltration improved the quality of secondary effluents as tertiary treatment. It successfully reduced the load of substances (microbes, dissolved organic matter, biopolymers, particles) reportedly contributing to fouling of subsequent membrane processes. Especially biopolymers of secondary effluents, which are major membrane foulants, were identified to be completely biodegradable. The biopolymers were estimated to be of colloidal size. Yet, the removal of these organics was suggested to be completely caused by biodegradation; neither filtration nor adsorption mechanisms played a role to retain biopolymers and dissolved organic carbon within the biofilter. However, a combined study of biofiltration and reverse osmosis revealed, that the improving effect of biofiltration as pre-treatment on membrane performance was lower than expected. Although, both biofouling and organic fouling were reduced on the reverse osmosis membrane, only marginal improvement on performance parameters was found. The adsorption of small non-biodegradable substances on the membrane as an organic fouling layer in the early stages of the process, as well as the difference in fouling layer composition were probably reasons for the findings. Thus, the successful application of biofiltration as pre-treatment is highly depending on the feed water source and the foulant layer formation. For the present case biofiltration as stand-alone pre-treatment is not recommended; a combination of biofiltration with subsequent e.g. flocculation and UF could be more beneficial.
APA, Harvard, Vancouver, ISO, and other styles
21

Li, Yu-Ling, and 李雨霖. "Hydrodynamics Analysis on Fluid Flow through Spiral Wound Membrane Modules." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/79466064323304805195.

Full text
Abstract:
碩士
中原大學
化學工程研究所
90
Effect of spacer design on fluid flow and separation efficiency in a spiral-wound module was conducted using computational fluid dynamic (CFD) technique. The spacer serves both as mechanical stabilizer for channel geometry and turbulence promoters for reducing polarization phenomena near the membrane surface. The turbulence promotion is based upon the flow around the woven threads of the spacer. Previously, several factors affect the pressure drop and mass transfer in a spacer-filled spiral-wound module have been studied based upon flat channel module. However, the curvature of the spacer varies along the spiral flow path. No any effort has been placed on the effects of curvature of the spacer and membrane permeability in the spiral-wound modules on the pressure drop, shear rate and separation efficiency through the curved module. Purposes of this study were emphasized on the effects of curvature of the spacer, fiber arrangement and membrane permeability in the spiral-wound modules on the pressure drop, shear rate and separation efficiency through the modules. Results showed that increase of the curvature of the spacer will result in increases of both the pressure drop and shear rate. On the other hand, the curved spacer in a spiral wound module causes unequal strain rate at inner and outer membrane surfaces. Such unequal shear rates at the inner and outer surfaces would be expected to have an adverse impact on the membrane module performance because of different fouling characteristics for adjacent membrane leaves. Results showed that decreasing of the diameter of outer fiber or increasing of the permeability of inner membrane can improve this adverse impact.
APA, Harvard, Vancouver, ISO, and other styles
22

Lu, Ming-Yang, and 呂明洋. "The Effects of Curvature on Fluid Flow through Spiral-Wound Membrane Modules." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/4cauxx.

Full text
Abstract:
碩士
中原大學
化學工程研究所
93
The feed spacer serves both as mechanical stabilizer for channel geometry and turbulence promoters for reducing polarization phenomena near the membrane surface. The turbulence promotion is based upon the flow around the woven threads of the spacer. In previous studies, factors affect the pressure drop and mass transfer in a spacer-filled spiral-wound module have been studied based upon flat channel module. However, the curvature of the spacer and channel varies along the spiral flow path. No effort has been placed on the effects of curvature of the spacer and channel in the spiral-wound modules on the pressure drop, flux and separation efficiency through the curved module.   Purposes of this work were emphasized on the effects of curvature of the spacer, fiber arrangement and the channel in the spiral-wound modules on the pressure drop, flux and separation efficiency through the modules. Results showed that increase of the curvature of the module will result in an increase of flux. The curved module in a spiral wound module causes unequal flux between inner and outer membrane layers. Such unequal flux through the inner and outer layers would be expected to have an unfavorable impact on the membrane module performance because of different fouling characteristics between each sides. An improvement analysis showed that decrease of the diameter of outer fiber or increase of the diameter of inner fiber can improve this adverse impact.
APA, Harvard, Vancouver, ISO, and other styles
23

"The performance of neurophysiologic monitoring to predict postoperative deficits in a porcine model of spinal cord injury." Thesis, 2010. http://library.cuhk.edu.hk/record=b6075031.

Full text
Abstract:
By observing these warning criteria, surgery can be safely carried out if changes of signal amplitudes are within the threshold boundary. Future studies should aim to validate and refine the "warning criteria" for intraoperative neurophysiologic monitoring in different surgery.
During stable anesthesia, experiments were completed in 31 pigs. A decrease in SEP amplitude > 25% and / or TceMEP amplitude > 65% was associated with substantial risk of postoperative motor deficit. In addition, rapid deterioration of signal within 5 min of an event, and / or a lack of signal recovery within 30 min after the initial deterioration were also predictors of postoperative paraplegia or weakness. These findings also correlated well with radiological changes in the spinal cord. The sensitivity and specificity for TceMEP to predict adverse neurologic outcome were 100% and 90.5%, respectively.
In a porcine model of direct compression and distraction of the exposed spinal cord, we measured the perioperative changes in SEP and TceMEP. This was correlated with postoperative motor function using the modified Tarlov scale. Magnetic resonance diffusion tensor imaging of the spinal cord was also performed to assess the anatomical extent of injury three days after surgery.
The spinal cord is at risk of injury during complex operations of the spine or aorta, and may result in catastrophic long term disability. Intraoperative monitoring with somatosensory evoked potential (SEP) and transcranial electric motor evoked potential (TceMEP) are commonly performed to assess the integrity of the sensory and motor pathways, respectively. The purpose of this study was to identify the minimum changes in signal amplitudes, beyond which postoperative neurologic deficit may occur.
Liu, Quanmeng.
Adviser: Matthew Tu Chan.
Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: .
Thesis (Ph.D.)--Chinese University of Hong Kong, 2010.
Includes bibliographical references (leaves 87-103).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
APA, Harvard, Vancouver, ISO, and other styles
24

Walker, Chandler L. "Targeting acute phosphatase PTEN inhibition and investigation of a novel combination treatment with Schwann cell transplantation to promote spinal cord injury repair in rats." Thesis, 2014. http://hdl.handle.net/1805/4210.

Full text
Abstract:
Indiana University-Purdue University Indianapolis (IUPUI)
Human traumatic spinal cord injuries (SCI) are primarily incomplete contusion or compression injuries at the cervical spinal level, causing immediate local tissue damage and a range of potential functional deficits. Secondary damage exacerbates initial mechanical trauma and contributes to function loss through delayed cell death mechanisms such as apoptosis and autophagy. As such, understanding the dynamics of cervical SCI and related intracellular signaling and death mechanisms is essential. Through behavior, Western blot, and histological analyses, alterations in phosphatase and tensin homolog (PTEN)/phosphatidylinositol-3-kinase (PI3K) signaling and the neuroprotective, functional, and mechanistic effects of administering the protein tyrosine phosphatase (PTP) inhibitor, potassium bisperoxo (picolinato) vanadium ([bpV[pic]) were analyzed following cervical spinal cord injury in rats. Furthermore, these studies investigated the combination of subacute Schwann cell transplantation with acute bpV(pic) treatment to identify any potential additive or synergistic benefits. Although spinal SC transplantation is well-studied, its use in combination with other therapies is necessary to complement its known protective and growth promoting characteristics. v The results showed 400 μg/kg/day bpV(pic) promoted significant tissue sparing, lesion reduction, and recovery of forelimb function post-SCI. To further clarify the mechanism of action of bpV(pic) on spinal neurons, we treated injured spinal neurons in vitro with 100 nM bpV(pic) and confirmed its neurprotection and action through inhibition of PTEN and promotion of PI3K/Akt/mammalian target of rapamycin (mTOR) signaling. Following bpV(pic) treatment and green fluorescent protein (GFP)-SC transplantation, similar results in neuroprotective benefits were observed. GFP-SCs alone exhibited less robust effects in this regard, but promoted significant ingrowth of axons, as well as vasculature, over 10 weeks post-transplantation. All treatments showed similar effects in forelimb function recovery, although the bpV and combination treatments were the only to show statistical significance over non-treated injury. In the following chapters, the research presented contributes further understanding of cellular responses following cervical hemi-contusion SCI, and the beneficial effects of bpV(pic) and SC transplantation therapies alone and in combination. In conclusion, this work provides a thorough overview of pathology and cell- and signal-specific mechanisms of survival and repair in a clinically relevant rodent SCI model.
APA, Harvard, Vancouver, ISO, and other styles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography